Improvement in machines for dressing cam-grooves



a. M. PRATT & vi A. KING.

Machines for Dressing Cam-Grooves.

Patented Feb. #1873.

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UNITED STATES PATENT OFFICE.

GEORGE M. PRATT AND VICTOR A. KING, OF MIDDLETOWN, CONNECTI- OUT, ASSIGNORS TO THE VICTOR SEWING-MACHINE COMPANY, OF

SAME PLACE.

IMPROVEMENT IN MACHINES FOR DRESSING CAM-GROOVES.

Specification forming part of Letters Patent No. 136,584, dated February 4, 1873.

To all whom it may concern:

Be it known that we, GEORGE M. PRATT and VIcToR A. KING, of Middletown, in the county of Middlesex and State of Connecticut, have invented a new Improvement in Machine for Dressing Grooved Cams; and we do hereby declare the following, when taken in connection with the accompanying drawing and the letters of reference marked thereon, to be a full, clear, and exact description of the same, and which said drawing constitutes part of this specification, and represents, in-

Figure 1, an end view; Fig. 2, a side view; Fig. 3, a top view; Fig. 4, a diagram illustrating a transverse section of the millingtool enlarged; and, in Fig. 5, a side view of the same.

This invention relates to a device for dressing the camgroove formed aroundthe periphery of cylinders, with special reference to the finishing of the cam-groove for that class of sewing-machines in which the needlebar is operated by a cylinder havinga camgroove formed around its surface. The groove in these cylinders is partially formed either by casting or milling, and then finished by hand to fit the pin or roll, which makes the expense of finishing this part of the machine no inconsiderable part of the whole. The object of this invention is to finish or dress this groove by an automatic device, avoiding the labor by hand; and it consists in a mandrel which revolves the cylinder having the cam that is to be finished combined with a toolholder which is pivoted distant from the axis of the said mandrel equal to the distance at which the cam-lever is to be pivoted on the machine for which the cam is designed.

A is the mandrel supported in suitable bearings B, and caused to revolve by the application of power thereto through a pulley, O, or otherwise. On this mandrel the cam-blank D to be finished is placed and secured by a thumb-screw, E, or otherwise, so that the cyl inder will revolve with the mandrel. F is the tool-holder, which is formed on the upper end of a tool-holding frame, G, the said frame I being pivoted at a, distance from the axial line of the cam equal to the length of the arm of the lever, which is to be worked by the said cam, the tool (1 in the holder having the relative position of the roll or pin in the end of the lever-arm, and which is to work in the groove or cam as the latter turns. The extreme diameter of the tool corresponds to the diameter of the said roll or pin. Its surface is cut, as seen in Figs. 4 and 5, the teeth or cutters being Ashape and running spirally around the surface, so as to work upon and dress both sides of the groove at the same time.

The cam-groove in the cylinder, as before mentioned, is shaped before placing it upon" the mandrel, and the tool follows in or is guided by this groove.

A longitudinal movement or feed can be imparted to the tool-holder G by means of a slide and a screw, H, so that by turning the screw the tool is thrown further into the groove or drawn therefrom, as the case may be.

In order to prevent the wearing of the tool at two points only a rotating movement is imparted to the tool by means of a lever, L, which is attached to the tool, so that by vibrating the said lever the tool will be rotated accordingly; and, to make this rotation automatic, we connect the arm of the lever L by a rod, N, or otherwise, to the frame, so that as the tool-holder G is thrown from one extreme to the other, as denoted in broken lines, Fig. 2, the arm of the lever being held, the tool will be rotated accordingly.

By this device the cam-groove is dressed in the most perfect manner, the tool, and likewise the' pin or roll, fitting the groove perfectly at all points.

We claim as our invention- 1. In combination with the mandrel A, to hold and revolve the blank D, the vibrating tool-holder G, the center of vibration being distant from the axial line of the cam equal, or nearly so, to the length of the arm to be revolved by the cam, substantially as described. I

2. The tool at for milling the groove of the cam, having the teeth out in A-form and running spirally around the tool, substantially as set forth.

GEO. M. PRATT.

Witnesses: VICTOR A. KING.

N. G. SHERMAN,

LN. CAMP. 

